Hydraulic pivot



July 22, 1958 w. v. RYDER, JR 2,844,415

HYDRAULIC PIVOT Filed Sept. 27, 1955 I 2 Sheets-Sheet 1 2 O I Flg. 2 46i ,.4 INVENTOR.

I WILLIAM V. RYDER, JR.

ATTORNEYS July 22, 1958 w. v. RYDER, JR 2,844,415

HYDRAULIC PIVOT Filed Sept. 27, 1955 2 Sheets-Sheet 2 ATTORNFYSnrnnanrro rivo'r William V. Ryder, in, Marhlehead, Mass assignor, bymesne assignments, to American Radiator & Standard Sanitary Corporation,New York, N. Y, a corporation of Delaware Appiication September 27,1955, Serial No. 537,017

7 Claims. (Cl. 308--2) This invention relates to pivotal mountings andprovides a new and improved pivot suitable for use in many types ofmeasuring instruments where large compressive forces are encountered.

One important object of my invention is to increase the lateral andcompressive load carrying capacity of pivoted mountings while retainingfree frictionless motion.

Another important object of my invention is to reduce frictional lossesin a pivot which employs bearings to define the pivotal axis by reducingthe load on the bearmgs.

To accomplish these and other objects my new and improved pivot includesas one important feature a sealed bellows filled with a substantiallyincompressible fluid having a low coeflicient of expansion. The fluidgives to the pivot great compressive load carrying capacity.

As another important feature my pivot includes a fixed plate rigidlyconnected to one end of the bellows, a second plate secured to the otherend of the bellows, and a link pivotally connected to each of theplates. This assembly furnishes lateral stability to the pivot.

These and other objects and features of my invention along with incidentadvantages will be better understood and appreciated from the followingdetailed description of a number of embodiments thereof selected forpurposes of illustration and shown in the accompanying drawing in which:I

Fig. l is a view in side elevation of a hydraulic pivot constructed inaccordance with this invention,

Fig. 2 is a plan View of the pivot illustrated in Fig. 1,

Fig. 3 is a view in cross-section of the pivot shown in Fig. 1, takenalong section line 33 of Fig. 2,

Fig. 4 is a view in cross-section of the pivot, taken along section line4i4 of Fig. 1,

Fig. 5 is a view in side elevation of another hydraulic pivotconstructed in accordance with this invention,

Fig. 6 is a plan view of the pivot shown in Fig. 5,

Fig. 7 is a view in cross-section of the pivot shown in Fig. 5, takenalong section line 7-7 of Fig. 6, and

Fig. 8 is a view in cross-section of the pivot taken along section line8-8 of Fig. 5.

The embodiment of my invention illustrated in Figs. 1-4 includes in itsgeneral organization a base 10, a bellows assembly 12 vertically mountedon the base 10, and a block 24 surmounted on the bellows assembly. Thebellows assembly 12 includes a bellows 13 which may be constructed ofextremely thin sheet steel, aluminum, or other material capable ofwithstanding high internal pressures.

The bellows is mounted coaxially about a cylindrical plug 16 formed witha base flange 14 which is soldered or welded to the bottom of thebellows, and the assembly is secured by the base flange to the uppersurface of the base it). To give the bellows 13 high compressivestability, the remaining portion of the bellows cavity is 2,844,415Patented July 22, 1958 filled with a substantially incompressible fluidsuch as glycerin or corn oil, and the cavity is sealed by a secondflange 22 connected to the upper end of the bellows.

The block 24 is secured by an upper flange 22 to the top of the bellowsassembly. The method of assembling the bellows mechanism will first bedescribed. Initially, the flange 14 of the plug 16 and the flange 22 aresecured to the ends of the bellows, and the assembly is mounted on thebase it). A bore 18 extending through the plug 16 and flange i4registers with a threaded pipe connection 20 in the base to providemeans for evacuating the bellows cavity. After the bellows is evacuated,a deaerated liquid is introduced into the cavity through the passage 18.A plug or similar device screwed into the connection 20 seals thepassage. Although the bellows will permit lateral movement of the blockrelative to the base in the absence of some restraining means, thecharged bellows restrains movement of the block toward the base andprovides a flexible support having high compressive load carryingcapacity. The block 24 consists essentially of a plate 23 having arecess 30 formed in its upper surface, and a cover 26 secured to theplate by a number of screws 38. A saddle 32 having vertical legs 34extending downwardly oneach side of the bellows is supported in therecess. The saddle 32 is somewhat narrower than the recess (see Fig. 3)and may be adjusted laterally by horizontal adjusting screws 36extending through the plate 28 into the recess. The cover 26 secured tothe plate retains the saddle in the recess but does not interfere withits lateral movement under the influence of the adjusting screws.

The saddle 32 is provided with downwardly extending legs 34 which arepivotally mounted by ball bearings 54 between opposed arms 52 of abifurcated link 40. The link as is hinged at its other end to the base10 by means of ears 44 formed in the base and ears 46 formed in the linkand connected to the studs by a pin 48.

The saddle 32 and link iii-provide a connection between the block 24 andthe base It resisting relative lateral motion but free to pivot andpermitting motion of the block and base toward each other.

It will be noted that the axis of the bearings perpendicularlyintersects the bellows axis approximately through the lowermost bellowsconvolution. It has been experimentally determined that such a locationof the axis minimizes the tendency for varying pressures Within thebellows to cause angular deflection of the pivot.

From the foregoing detailed description of the embodiment of theinvention illustrated in Figs. 1-4 it will be seen that a force exertedvertically down on the block with its line of direction passing throughthe center of the bearing axis is opposed by the incompressible bellows;thus the block does not move appreciably. The bearings, therefore,receive substantially none of the load applied vertically to the device,and any couple which tends to pivot the block about the bearings is notresisted by large bearing friction. Since, however, all liquids are tosome degree compressible, the bellows does not completely eliminatevertical movement of the block. The hinged connection between thesupport 42 and the link 40 is provided to compensate for anyforeshortening of the bellows under the influence of the impressedforces, i. e. the connection allows the bearing assembly to movedownwardly with the block so that the entire vertical load is borne bythe slightly compressed bellows.

Assume that the vector P illustrated in Fig. 1 represents the impressedforce. As has been demonstrated, the vertical component V of the vectordoes not substantially affect the position of the block or the bearings.The link and the member 32 resist translational movement of the blockunder the influence of the horizontal component 12 of the force.However, the bearing assembly does permit the horizontal component 12 todisplace the block angularly about the bearing axis, and the pivotalmovement of the block will be substantially frictionless.

If the force F is applied 90 degrees from the position illustrated sothat the horizontal component [2 lies perpendicular to the plane of thepaper, translational movement of the block will be opposed by the hingesupport 42 rigidly connected to the link. A spacer 5t) separating thestuds 44 and ears 46 prevents axial movement of the link 32 on the hingepin 48. Because the bellows resists movement of the block 24 under theinfluence of the vertical component v of the force and the horizontalcomponent It is opposed by the support 42 and the hinge 40, the positionof the block does not change.

The foregoing analysis demonstrates that the mechanism establishes afixed pivotal axis comparable to that of a knife edge and anvil. lysmall because the vertical component of a load applied to the block 24is supported by the bellows and not the bearings. Bearing friction maybe affected only by increases in the horizontal component of forcesimpressed on the block. These characteristics of the device render itparticularly well suited to resist forces having large verticalcomponents as compared to the magnitude of its horizontal component. Thedevice will render long service without appreciable wear.

The instrument illustrated in Figs. 5-8 is very similar to theembodiment of this invention described above. The addition of a secondbellows in the assembly, however, permits damping of the movement of theblock and otherwise provides advantages not obtained from the simplerembodiment. in detail, a base 62 carries a pair of bellows assemblies 64comprising flanges 66 and 67, plugs 68 and the bellows 59. The lowerbellows flanges 66 may be secured to the base by welding or otherappropriate means. Lateral passages 70 in each of the plugs communicatewith vertical passages 72 formed in the flanges 66 and the base 62, andtogether with the interconnecting passage 74, provide access to thebellows chambers. A threaded pipe connection 75 at the end of thepassage '74 permits evacuating and charging of the bellows chambers inthe manner described in the preceding embodiment.

Studs integrally formed with the flanges 67 hold a block '76 on top ofthe bellows assemblies 64. pins 84 driven through the block 76 and intothe flanges 67 prevent relative twisting of those elements. Verticalflanges 78 extend downwardly from the block '76 and receive a horizontalpivot shaft M92 positioned between the bellows assemblies 64.

The components which complete the mechanism are similar to thecorresponding components of the preceding embodiment. A hinge support 86cast with the base has a pair of ears 88 which mate with cars 94 of alink 90. A hinge pin 96 interconnects the ears $8 and 94- and permitsthe link to pivot about the pin axis. A pair of arms 92 forming part ofthe link 96} extend horizontally from the ears 5 4 and terminate aboutthe axis of the shaft 1012. Bearing assemblies 100 support the shaft 102in the terminal portions of the arms 92. The shaft 102, the bearingassemblies 100, and the bellows s9 define the pivotal axis about whichthe block moves under the influence of impressed forces.

In use, the bellows chambers along with the passages 70, 72, and 74 arefilled with an incompressible liquid. Unable to compress, each of thebellows resists vertical movement of the block, thus shielding thehearing assemblies 100 from all vertical forces passing through thepivotal if a torque is applied about the axis of the shaft 102, fluidtransfers from one bellows to Frictional losses are extreme-- Dowel tit)the other through the interconnecting passages. The transfer of liquidresults in substantially frictionless angular displacement of the block76 about the axis of the shaft 192. The link and the hinge support 86resist all translational movement of the block in the same manner as setforth in the description of the preceding embodiment.

It is often desirable to deaden the effects of sudden extraneous forcessensed by the device. The passage 7 provides ready means for dampeningthe system. By introducing a partial restriction or orifice 1% into thepassage, the rate of flow of the fluid between the bellows is reducedand instantaneous forces applied to the block have little or no effect.

From the foregoing description, the advantages of the hydraulic pivotsmay be fully appreciated. Either of the assemblies may be incorporatedinto any device which requires a substantially frictionless fulcrum.They pro vide a pivotal axis as clearly defined as the fulcrum of aknife edge assembly.

Those skilled in the art will readily appreciate that numerousmodifications of the illustrated embodiments may be made withoutdeparting from the spirit of my invention. Therefore, it is not intendedthat the scope of my invention be limited to those embodimentsillustrated and described, but that its breadth be determined by theappended claims and their equivalents.

Having thus disclosed my invention What I claim as new and desire tosecure by Letters Patent of the United States is:

1. A hydraulic pivot comprising a pair of spaced apart rigid members, apair of parallel bellows rigidly secured between said members chargedwith an incompressible fluid, a passage providing fluid communicationbetween said bellows, and linking means interconnecting said membershaving hingedly connected portions providing a pivotal axis for saidmembers between said bellows perpendicular to the bellows axes.

2. A hydraulic pivot as defined in claim 1 further characterized bydamping means in said passage retarding fluid flow through said passage.

3. A hydraulic pivot comprising a pair of spaced apart members, anincompressible bellows assembly rigidly secured to each of said memberswith the assembly axis perpendicular to each of said members, a linkpivotally secured to one of said members along an axis perpendicular toand intersecting the axis of said bellows assembly, and a pivotalconnection between said link and the other of said members disposedparallel to the pivotal connection of said link and the first namedmember.

4. A hydraulic pivot comprising a pair of spaced members, a pair ofparallel bellows each of which is secured at each end to one of saidmembers, a passage providing fluid communication between said bellows,said passage and said bellows being charged with a substantially incompressible fluid, and a link hinged upon a first one of said membersand having a pair of arms pivotally connected to the second member, thepivot connection of the arms of the link and said second member beingdisposed along an axis perpendicular to and intermediate the long axesof said bellows.

5. A hydraulic pivot as defined in claim 4 wherein the hinge connectionof the link to said first member is disposed about an axis parallel tothe axis of the pivot connection between the arms of the link and saidsecond member.

6. A hydraulic pivot as defined in claim 4 wherein damping means isprovided in said passage to retard the flow of fluid therethrough.

7. A hydraulic pivot comprising first and second members, a bellowssecured at each end to one of said members, a saddle-shaped memberadjustably secured to the first of said members and having parallel endmembers extending toward the second member, a link hinged to said secondmember and having a pair of arms pivotally connected to the end membersof said saddle-shaped mem- References Cited in the file of this patenther, the pivot connection between the end members and arms of the linkbeing disposed along an axis perpendicu- UNITED STATES PATENTS lar tothe long axis of the bellows, and means disposed in 1,352,441 E nght eta1 Sept. 14, 1920 one of said members forming a passage to the interiorof 5 1,425,979 Kmgsbury Aug. 15, 1922 the bellows. 2,307,590 Kenyon Jan.5, 1943

